As far as the v3.2 2003-03-30 that I'm using goes...

I think everything you need's already in /usr/src, except for the source codes for the kernel and the xfs kernel patch, which can be d/l'd from debian.org as .deb packages. You'll also want to apply knoppix-kernel.patch, which raises the character limit for the boot prompt from 256 to 512 characters. You can ignore the xfs patch if you don't plan on supporting the xfs filesystem.

Specific info in /usr/src/kernel-source.README.

Not sure what the purpose of the included linux-2.4.20-xfs directories and the ptrace patch may be (didn't check), but nothing's blown up as a result of my ignoring them